﻿var _ga = _ga || {};
var _gaq = _gaq || [];

/**
* Helper method to track social features. This assumes all the social
* scripts / apis are loaded synchronously. If they are loaded async,
* you might need to add the nextwork specific tracking call to the
* a callback once the network's script has loaded.
* @param {string} opt_pageUrl An optional URL to associate the social
*     tracking with a particular page.
* @param {string} opt_trackerName An optional name for the tracker object.
*/
_ga.trackSocial = function(opt_pageUrl, opt_trackerName) { 
    _ga.trackFacebook(opt_pageUrl, opt_trackerName);
};

/**
* Tracks Facebook likes, unlikes and sends by suscribing to the Facebook
* JSAPI event model. Note: This will not track facebook buttons using the
* iFrame method.
* @param {string} opt_pageUrl An optional URL to associate the social
*     tracking with a particular page.
* @param {string} opt_trackerName An optional name for the tracker object.
*/
_ga.trackFacebook = function(opt_pageUrl, opt_trackerName) {
    var trackerName = _ga.buildTrackerName_(opt_trackerName);
    try {
        if (FB && FB.Event && FB.Event.subscribe) {         
            FB.Event.subscribe('edge.create', function(targetUrl) {            
                _gaq.push([trackerName + '_trackSocial', 'facebook', 'like',
            targetUrl, opt_pageUrl]);
            });
            FB.Event.subscribe('edge.remove', function(targetUrl) {
                _gaq.push([trackerName + '_trackSocial', 'facebook', 'unlike',
            targetUrl, opt_pageUrl]);
            });
            FB.Event.subscribe('message.send', function(targetUrl) {
                _gaq.push([trackerName + '_trackSocial', 'facebook', 'send',
            targetUrl, opt_pageUrl]);
            });
        }
    } catch (e) { }
};


/**
* Returns the normalized tracker name configuration parameter.
* @param {string} opt_trackerName An optional name for the tracker object.
* @return {string} If opt_trackerName is set, then the value appended with
*     a . Otherwise an empty string.
* @private
*/
_ga.buildTrackerName_ = function(opt_trackerName) {
    return opt_trackerName ? opt_trackerName + '.' : '';
};


/**
* Extracts a query parameter value from a URI.
* @param {string} uri The URI from which to extract the parameter.
* @param {string} paramName The name of the query paramater to extract.
* @return {string} The un-encoded value of the query paramater. underfined
*     if there is no URI parameter.
* @private
*/
_ga.extractParamFromUri_ = function(uri, paramName) {
    if (!uri) {
        return;
    }
    var uri = uri.split('#')[0];  // Remove anchor.
    var parts = uri.split('?');  // Check for query params.
    if (parts.length == 1) {
        return;
    }
    var query = decodeURI(parts[1]);

    // Find url param.
    paramName += '=';
    var params = query.split('&');
    for (var i = 0, param; param = params[i]; ++i) {
        if (param.indexOf(paramName) === 0) {
            return unescape(param.split('=')[1]);
        }
    }
    return;
};
